1. Field of the Invention
The invention is directed to a process for producing a heat exchanger whose extension in flow direction of an outer heat exchanger medium is dimensioned so as to be substantially greater than the height thereof, wherein separately manufactured ribs are connected to the exchanger tubes in a continuous manner and the ribbed exchanger tubes are subsequently galvanized. The invention is also directed to an apparatus for implementing the process.
2. Description of the Related Art
A heat exchanger is known from DE-PS 34 19 734 by means of which heat can be exchanged e.g. between gases and liquids or between gases and condensing vapors. Such a heat exchanger is used predominantly to cool air or to condense vapors by means of air.
Steel ribs in particular, specifically dip-galvanized steel ribs, are used in connection with steel exchanger tubes. Such ribs are punched from plates or strips on corresponding machines and are slid onto the exchanger tubes in the longitudinal direction. The subsequent galvanization in the immersion bath serves not only to protect the exchanger tubes and the ribs, but also simultaneously produces the metallic connection of the exchanger tubes with the ribs.
The exchanger tubes, which are slender in the direction of flow of the external heat exchanger medium and oval in principle, are arranged so as to be adjacent to one another in at least one row between tube bases at the ends. The tube ends are rolled or welded in the tube bases. Stable supporting constructions are made use of in addition to the tube bases for connecting the exchanger tubes.
When manufacturing the known heat exchanger it is necessary that the mechanical processes for punching out and sliding the ribs on the exchanger tubes be effected with great precision so as to ensure the most intimate possible connection of the exchanger tubes with the ribs. A considerable expenditure is required for this. Further, since the ribs are slid over the exchanger tubes, the punched out material in the cross section of the exchanger tubes makes up a considerable proportion in terms of weight and is mostly scrapped without being utilized.
If the exchanger tubes are galvanized individually, every exchanger tube is first pressed flat at its ends and tightly welded so that only the outer surfaces are pickled and passivated and a galvanizing of the inner surfaces is prevented. This also requires a considerable expenditure. After galvanizing the exchanger tubes the flattened and welded ends must be removed. This likewise involves additional work time and material waste which is not recoverable in principle.
It is then necessary to join the individual exchanger tubes via the aforementioned supporting constructions to form heat exchangers which must be self-supporting along their length.
Thus, in the known case, the production of a heat exchanger involves relatively costly and time-consuming work steps. In addition, the manufacturing sequences are made more difficult by steps for preventing damage to the surface protection afforded by the galvanizing during the assembly of the heat exchanger.
As a result of internal vacuum pressure and/or external excess or over-pressure, substantial forces act on the large surface area flanks of the slender exchanger tubes. As a result, the tube flanks are pressed in when a determined degree of slenderness is exceeded if suitable measures in the form of supports are not provided. In this regard it has been suggested to support the tube flanks relative to one another by at least one inner transverse web.